Notify your doctor if you experience serious side effects of Synthroid including rapid heartbeat, fluttering in your chest, or chest pain.

Synthroid is prescribed in tablets that range from 25 to 300 mcg in strength and is usually taken once a day with a full glass of water (about 8 ounces) 30 to 60 minutes before breakfast for best adsorption into the body. Children can take the medicine if the tablet is crushed and put into about 1 to 2 teaspoons of water; do not store or delay giving this crushed pill suspension. Doctors often may have to slowly increase the dose; patients should not increase or decrease this medication themselves. Because some preparations of the drug may contain iodine or lactose, patients should tell their doctors about such allergies or reactions to these components. Many drugs can inhibit Synthroid's adsorption by the body; other medications may increase or decrease its effectiveness once it is adsorbed. Providing a complete list of medications to the doctor will help with getting the correct dose established for each individual patient. Pregnant and lactating females need to discuss the dose and use of this medication with their caregivers.

Our Synthroid Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Respiratory

Gastrointestinal

Dermatologic

Endocrine

Reproductive

menstrual irregularities, impaired fertility.

Pseudotumor cerebri and slipped capital femoralepiphysis have been reported in children receiving
levothyroxine therapy. Overtreatment may result in craniosynostosis in infants and premature closure of
the epiphyses in children with resultant compromised adult height.

Seizures have been reported rarely with the institution of levothyroxine therapy.

Inadequate levothyroxine dosage will produce or fail to ameliorate the signs and symptoms of
hypothyroidism.

Hypersensitivity reactions to inactive ingredients have occurred in patients treated with thyroid
hormone products. These include urticaria, pruritus, skin rash, flushing, angioedema, various GI
symptoms (abdominal pain, nausea, vomiting and diarrhea), fever, arthralgia, serum sickness and
wheezing. Hypersensitivity to levothyroxine itself is not known to occur.